SAPWOOD

n. new soft wood located beneath the bark, part of a tree that conveys water and sap

For the NATO reporting name for the R-7 Semyorka intercontinental ballistic missile, see SS-6 Sapwood. Sapwood is the outer layer of wood in a tree, next to the bark. Sapwood will mature into Truewood as the tree grows. See also wood#Heartwood and sapwood.
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Noun
1. newly formed outer wood lying between the cambium and the heartwood of a tree or woody plant; usually light colored; active in water conduction
(hypernym) wood
(substance-holonym) tree

(n.)
The alburnum, or part of the wood of any exogenous tree next to the bark, being that portion of the tree through which the sap flows most freely; -- distinguished from heartwood.
  

n.
آسرا, (رس چوب, رس خام)